2$2 Dr. Pearson’s Experiments for 
I 
alkali will not yield phosphorus by exposure to charcoal and 
heat, unless plumbum corneum be added, we cannot infer that 
the carbonic acid in mild mineral alkali will be decompounded 
by phosphorus ; because, as in the case of bone-ashes and phos- 
phorus, the joint affinities between respirable air and phos- 
phorus, and between phosphoric acid and mineral alkali, are, 
by this fact, shown to be not inferior to the conjoined affinities 
between charcoal and respirable air, and between carbonic 
acid and that alkali. No other conclusion can be drawn with 
respect to the affinities exerted when charcoal is applied to 
phosphorated vegetable alkali ; because the affinity is stronger 
between the phosphoric acid and vegetable alkali, than be- 
tween the same acid and mineral alkali. As the attractive forces 
between phosphoric acid and barytes, and between that acid 
and magnesia are, very probably, at least equal to those be- 
tween phosphoric acid and fixed alkalies, the question, whe- 
ther carbonic acid united to these earths can be decomposed 
by phosphorus, remains to be determined by experiments. But 
with respect to the volatile alkali, we know, by the experience 
of making phosphorus from urine, that the united affinities 
betw een respirable air and phosphorus, and between phosphoric 
acid and volatile alkali, are inferior to the joint affinities be- 
tween charcoal and respirable air, and carbonic acid and vo- 
latile alkali ; hence, in a due degree of heat, phosphorus and 
mild volatile alkali are formed from phosphorated volatile al- 
kali and charcoal, consequently carbonic acid combined with 
volatile alkali, cannot be decompounded by phosphorus and 
heat, even if the volatility of that alkali did not, apparently, 
render it impossible to apply the requisite degree of heat. We 
know so little of the degree of chemical attraction betwixt clay 
